JSM 2013: A multilevel mediation model


In a longitudinal cluster randomized study, we investigate the role of the quality of instruction in mediating the effect of a new inquiry-based learning approach for teaching science, the Science Writing Heuristic (SWH), to Iowa students in third, fourth, and fifth grades. There are 48 schools (clusters) participating in the study, with a total of roughly 2300 students per grade per year enrolled in the schools. The students’ standardized test scores in math, reading, and science were collected each year. We are primarily interested in student-level outcomes and in quality of implementation at the teacher level as a mediator of those outcomes. The method for teaching science was assigned randomly to the school building; given this configuration, we will use a 3-2-1 mediation design (Pituch et al., 2010). We will also investigate whether other socioeconomic, sociodemographic, or learning variables moderate the indirect or direct effects of the SWH approach on the student-level outcomes (Matsumura et al., 2013).

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